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/* $NetBSD: pidfile.c,v 1.2 2016/04/05 12:28:57 christos Exp $ */
/*-
* Copyright (c) 1999 The NetBSD Foundation, Inc.
* All rights reserved.
*
* This code is derived from software contributed to The NetBSD Foundation
* by Jason R. Thorpe, Matthias Scheler and Julio Merino.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
* ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
* TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
* PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
* BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
* POSSIBILITY OF SUCH DAMAGE.
*/
#ifdef HAVE_CONFIG_H
#include "config.h"
#endif
#include <sys/cdefs.h>
#if defined(LIBC_SCCS) && !defined(lint)
__RCSID("$NetBSD: pidfile.c,v 1.2 2016/04/05 12:28:57 christos Exp $");
#endif
#include <sys/param.h>
#include <paths.h>
#include <stdbool.h>
#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include <unistd.h>
#ifdef HAVE_LIBUTIL_H
#include <libutil.h>
#endif
#ifdef HAVE_UTIL_H
#include <util.h>
#endif
static pid_t pidfile_pid;
static char *pidfile_path;
/* Deletes an existent pidfile iff it was created by this process. */
static void
pidfile_cleanup(void)
{
if ((pidfile_path != NULL) && (pidfile_pid == getpid()))
(void) unlink(pidfile_path);
}
/* Registers an atexit(3) handler to delete the pidfile we have generated.
* We only register the handler when we create a pidfile, so we can assume
* that the pidfile exists.
*
* Returns 0 on success or -1 if the handler could not be registered. */
static int
register_atexit_handler(void)
{
static bool done = false;
if (!done) {
if (atexit(pidfile_cleanup) < 0)
return -1;
done = true;
}
return 0;
}
/* Given a new pidfile name in 'path', deletes any previously-created pidfile
* if the previous file differs to the new one.
*
* If a previous file is deleted, returns 1, which means that a new pidfile
* must be created. Otherwise, this returns 0, which means that the existing
* file does not need to be touched. */
static int
cleanup_old_pidfile(const char* path)
{
if (pidfile_path != NULL) {
if (strcmp(pidfile_path, path) != 0) {
pidfile_cleanup();
free(pidfile_path);
pidfile_path = NULL;
return 1;
} else
return 0;
} else
return 1;
}
/* Constructs a name for a pidfile in the default location (/var/run). If
* 'basename' is NULL, uses the name of the current program for the name of
* the pidfile.
*
* Returns a pointer to a dynamically-allocatd string containing the absolute
* path to the pidfile; NULL on failure. */
static char *
generate_varrun_path(const char *bname)
{
char *path;
if (bname == NULL)
bname = getprogname();
/* _PATH_VARRUN includes trailing / */
if (asprintf(&path, "%s%s.pid", _PATH_VARRUN, bname) == -1)
return NULL;
return path;
}
/* Creates a pidfile with the provided name. The new pidfile is "registered"
* in the global variables pidfile_path and pidfile_pid so that any further
* call to pidfile(3) can check if we are recreating the same file or a new
* one.
*
* Returns 0 on success or -1 if there is any error. */
static int
create_pidfile(const char* path)
{
FILE *f;
if (register_atexit_handler() == -1)
return -1;
if (cleanup_old_pidfile(path) == 0)
return 0;
pidfile_path = strdup(path);
if (pidfile_path == NULL)
return -1;
if ((f = fopen(path, "w")) == NULL) {
free(pidfile_path);
pidfile_path = NULL;
return -1;
}
pidfile_pid = getpid();
(void) fprintf(f, "%d\n", pidfile_pid);
(void) fclose(f);
return 0;
}
int
pidfile(const char *path)
{
if (path == NULL || strchr(path, '/') == NULL) {
char *default_path;
if ((default_path = generate_varrun_path(path)) == NULL)
return -1;
if (create_pidfile(default_path) == -1) {
free(default_path);
return -1;
}
free(default_path);
return 0;
} else
return create_pidfile(path);
}
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